The invention relates to data carriers having ring-shaped metallic lamina in each data location and means for removing portions of predetermined lamina and means for reading the information on the data carriers resulting from the removal of the ring portions.
The data carriers are used in various fields including for instance, identity cards, admission tickets, or contactless incremental transmitters where the information in the form of metal lamina is put on electrically nonconducting cards or plates of plastic or other synthetic material. The existence or nonexistence of these lamina in spatially fixed places on the carrier cards determines the data content of such carriers. The information may be placed on the cards either by gluing prefabricated metal lamina onto one surface of the cards or by etching off metal films which were previously placed on the cards. The recognition of the metal lamina is based on the decrease of the electromagnetic coupling between two coils when the metal lamina is passed between the coils.
These well-known processes for placing of the desired information on a data carrier have the disadvantage that they can be carried out only with the help of expensive and complex machinery, therefore, being generally practical only at the place where the data carriers are produced. Production of the data carriers at one central location and placing the information on the data carriers at many decentralized locations with the use of simple and hence inexpensive arrangements is therefore not possible.
The invention is based on the concept of developing a process of placing the information on the cards which permits a simple and reliable notation of the desired information on the data carriers or cards without the complex machinery of the prior art.
The problem is solved by the invention by placing ring-shaped metal lamina on each data location intended for utilization. The desired information is then placed on the data carrier by removing a portion of the rings in predetermined locations in such a way that the formation of the short-circuit current, which originates under the influence of a magnetic field, is prevented by the removed portion of the rings and therefore the magnetic coupling is not decreased during inductive reading or scanning.
For instance, identification cards may be produced uniformly and efficiently by means of the invention and the programming or placing of the information takes place in a simple and reliable manner by the individual user of the identification card, for instance, the respective branch banks of a central bank. In a like manner, the contactless incremental transmitters or program transmitter plates, which are adjusted to the needed control functions at each users location, can be etched uniformly.
In one embodiment of the invention the removal of a portion of the ring takes place by melting off the ring portion. Preferably, the melting off takes place by means of a capacitor discharge from a capacitor which is charged to a correct level from a direct current source through a compensating resistance. The ring portion may also be melted off by means of a short-circuit current induced in the ring of a sufficient magnitude. For instance, the short-circuit current may be provided by means of a transmitter coil such as present in a reading device which is fed by a high frequency source.
The apparatus or arrangement for melting off the desired ring portions may consist of a pair of electrodes connected to a capacitor with a compensating resistor and a direct current source or battery connected to the capacitor. The apparatus may be designed as a hand-held crayon-like cylinder. The apparatus may have a lamp connected in parallel with the capacitor, with the brightness of the lamp indicating the state of charge of the capacitor, and which thereby will signal the removal of the ring portion by a momentary extinguishing of the lamp when the capacitor is discharged.
According to another embodiment of the invention, the ring portion may be mechanically removed.
The invention also relates to a system for inductive reading of the data or information which is placed on the nonconductive card-shaped carriers by means of metallic information elements placed on the carriers in predetermined locations. Card-shaped and machine readable data carriers having the information carried thereon by the existence or nonexistence of metallic lamina are employed to an increasing extent for identification, transportation tickets and admission tickets. Compared to other types of data carriers which can be read optically or magnetically, this type of data carrier with metallic lamina on one surface has the advantage of being a great deal more sturdy. The additional advantages of security against visual recognition or reading and security against fraud are produced by locating the metallic lamina between two opaque and inseparable layers of the data carrier.
The prior well-known reading reading devices for the recognition of metallic lamina information elements consist of several reading places each of which consist of a coil for the generation of a magnetic field, whose magnitude changes with time, and a secondary associated coil. Voltage is induced in the secondary coil which is proportional to the magnitude and time change of the primary coupling magnetic field and whose amplitude is utilized for the recognition of the information. A lower voltage is induced if a metallic lamina is moved between the primary and secondary coil because of the short-circuit current induced in the lamina. The generation of the magnetic field may take place by a generator or, for instance, also by a capacitor discharge. The individual data locations may be controlled and read simultaneously or in groups in a predetermined chronological order. The metallic information elements are usually solid flat metallic lamina.
The previous reading arrangements have the disadvantage that for the recognition of the data or information they require a relatively large reduction of the coupling of the magnetic coupled field and therefore require metallic information elements with a large surface dimension. These reading devices also are not provided with an automatic transport device so that the carrier or card is pushed into the reading device up to a mechanical stop and then subsequently the data or information is read from the card. Reading units, consisting of a primary and secondary coil, must therefore be provided for each possible data location.
The invention also includes a noncomplex device for the inductive reading of the data which makes possible reliable recognition of very small dimensioned metallic information elements. Furthermore, a data carrier of the invention includes data locations for the control of the reading device in such a way that the corresponding reading device contains a substantially fewer number of reading units without having a motor drive or other automatic transport device. The cards are also provided with orientation lamina so that the reading device will correctly recognize the information content of the card independent of the position or orientation of the card in the reading device.
Each reading unit of the inductive reading device consists of a transmitting coil generating a magnetic alternating flux and two receiving coils which are electrically coupled to one another by means of a bridge circuit and which are spatially arranged relative to one another such that the voltage in each receiving coil is of the sample amplitude and the same phase. When a magnetic information element passes between the coils causing a short-circuit current in the element the alternating magnetic field is influenced in such a way that the proportion of the alternating voltage induced in the two receiving coils changes and the bridge circuit is detuned.
In the reading device of the invention, several reading units are arranged adjacent to one another and one reading unit after the other is switched on in a chronologically determined sequence by a control mechanism for scanning the information contents of a series of information or data locations.
The invention also includes a data carrier having the rings of the invention to be utilized in the reading device of the invention. The data carrier may have several rows or channels of the metallic rings on an electrically nonconducting carrier material. Each ring of the data carrier may have a narrow cross-bar to provide the portion of the ring which is to be removed where desired.
Two inductively readable control channels are placed on the data carrier to trigger the reading cycle of the reading device as well as for the timing control for the storing of the data. The control tracks or channels also indicate the moving direction of the card to the reading device. Two orientation lamina or otherwise inductively readable marks are placed on the data carrier in a spatial arrangement such that the reading device, which scans the orientation lamina at the beginning of the reading action, detects which of the four possible positions the data carrier card has been placed in the reading device.